The object of orthodontic operations is to treat tooth irregularities. Tooth irregularities are often treated by exerting tractive or compressive forces on the teeth which are to be treated. For this purpose a first end of a surgical element for exerting a tractive or compressive force (called a traction element in the following for the sake of simplicity) is fastened to a tooth which is to be treated. The other end of the traction element was in the past frequently fixed to another tooth. However the disadvantage in this respect is that this other tooth also gradually changes its position on account of the counterforce acting on it. This is undesirable in most cases.
This was the reason for the development of anchor devices so as to avoid having to fasten the free end of a traction element fastened to a tooth which is to be treated to another tooth. As a rule, anchor devices of this kind comprise a fixing device which can be fixed in or to a bone as well as a retaining device, coupled to the fixing device, for the traction element.
An anchor device of this kind is known from WO 02/02023 A, for example. The known anchor device has a fixing device in the form of a linear bone plate which is fastened on a jaw-bone by means of suitable bone screws. The bone plate is connected to a hook-like retaining device for a traction element.
A further anchor device is described in WO 02/091941 A. The anchor device in the latter likewise comprises a fixing device in the form of a bone plate as well as a retaining device connected to the bone plate (by means of an L-shaped intermediate piece). The retaining device has a spherical head through which two through-openings pass, these extending perpendicularly to one another. The through-openings function as a locating region for a traction element having the shape of a wire, for example. A clamping force which fixes the traction element in the through-openings can be produced by means of a clamping screw extending perpendicularly to the through-openings.
An anchor device which is known from EP 0 823 244 A has a fixing device in the form of a pin or a screw which can be fastened directly in a bone. A hook is provided as retaining device for the traction element, which hook is retained at a spacing from the fixing device by means of an arm.
A further anchor device with a fixing device formed as a bone screw is described in U.S. Pat. No. 6,575,742 B. This anchor device comprises a screw head, extending co-linearly with the bone screw, with a retaining device for the traction element. The retaining device is formed as a through-opening which passes through the screw head perpendicularly to the screw shank. The screw head also has a circumferential depression for fastening a traction element in the form of a wire loop or a rubber band.
The object underlying the invention is to provide a device for anchoring a surgical traction element in the mouth region which can be easily handled.